The Iranian government today urged the country's media to refrain from insults after a hardline newspaper twice described Carla Bruni-Sarkozy, France's first lady, as a "prostitute".

The Keyhan daily paper made the comments after Bruni-Sarkozy condemned the stoning sentence against an Iranian woman convicted of adultery.

Ramin Mehmanparast, a foreign ministry spokesman, said insulting foreign dignitaries was incorrect and was not officially sanctioned.

The paper first called Bruni-Sarkozy a prostitute on Saturday and repeated the comment today. It said that, like Sakineh Mohammadi Ashtiani, the woman sentenced to stoning, Bruni-Sarkozy deserved to die, as did actor Isabelle Adjani, who also condemned the sentence.

Ashtiani, whose sentence has been suspended, could still face execution after a review of her case, which has prompted international outrage that appears to have rattled the authorities in Tehran.

The mother of two has already received 99 lashes for having an illicit relationship with two men.

Bruni-Sarkozy was one of several French celebrities who published open letters to Ashtiani.

"In the depths of your cell, know that my husband will plead your cause unfailingly and that France will not abandon you," she wrote.

"Spill your blood, deprive your children of their mother? Why? Because you have lived, because you have loved, because you are a woman, an Iranian? Every part of me refuses to accept this."

Today, it returned to the subject, criticising Bruni's "illicit relationships with various people" and blaming her for causing Nicolas Sarkozy's divorce from his second wife.

"Studying Carla Bruni's record clearly shows the reason why this immoral woman is backing an Iranian woman who has been condemned to death for committing adultery and being an accomplice in her husband's murder and, in fact, she herself deserves to die," the paper said.

"Bruni is the singer and decadent actress who managed to break the Sarkozy family and marry the French president."

Mehmanparast called on Iran's media to use more temperate language. "Insulting the officials of other countries and using inappropriate words … is not approved of by the Islamic Republic of Iran," he said.

"The policies, the manners and the comments of other countries' officials, we criticise them, we make objections to them and we call for them to review their deeds, but we don't think using inappropriate words and insulting words is the right thing to do."

However, Iranian state-run TV also described Bruni-Sarkozy as "proud of her immoral acts".

Earlier this month, an Iranian vice-president attacked Britons as "inhuman" idiots saddled with a dunce of a prime minister.

The president, Mahmoud Ahmadinejad, urged Americans to "pour water where it burns", a reference to a phrase about people who are so angry that their buttocks catch fire.